1. Field of Invention
The invention relates to the technical field of a vehicular seat apparatus which is mounted in a vehicle and is constructed to be capable of adjustment, e.g., adjusting the fore-and-aft position of a seat or the fore-and-aft position and the vertical height thereof.
2. Description of Related Art
Generally, some seat apparatuses mounted in vehicles are constructed such that the seat can be moved by, e.g., a fore-and-aft position adjusting means or a fore-and-aft position and vertical height adjusting means. Such a seat apparatus often employs an electric motor as a power source for moving the seat. In this case, an electric motor 11 is mounted, by way of example, as shown in FIGS. 3A and 3B. Frame members 13, 14 having extensions having threaded holes 13a, 14a formed therein are fixed to opposite axial ends of a yoke 12 of the electric motor 11 by caulking or any other fixing means. The electric motor 11 is disposed between a pair of mounting brackets 15, 16 which are arranged in an opposed relationship in the axial direction of a motor shaft 11a. The electric motor 11 is then secured by inserting screws 17 from respective outer surfaces of the mounting brackets 15, 16 and tightening the screws into the threaded holes 13a, 14a. With such a structure, the electric motor 11 can be firmly fixed in place with less vibration while both the motor axial ends are fixedly supported to the mounting brackets 15, 16.
The above-described related art however has problems as follows. Because the screws 17 are fastened to the frame members 13, 14 at the axial opposite ends of the electric motor 11 from the outer surfaces of the mounting brackets 15, 16 on both the axially spaced sides, the spacing between the mounting brackets 15, 16 must be in good match with the axial length (mounting dimension) of the electric motor 11 provided with the frame members 13, 14. Meanwhile, each component has a variation in product dimension which is inevitably caused during the manufacture process. Further, the frame members 13, 14 are fixed to the opposite ends of the electric motor 11 through fixing means as mentioned above. Particularly when the frame members 13, 14 are fixed by caulking, it is difficult to keep the mounting dimension of the electric motor 11 constant due to the inevitable variations in size produced by the caulking. If the spacing between the mounting brackets 15, 16 is not in match with the mounting dimension of the electric motor 11, gaps are left between outer end faces of the extensions having the threaded holes 13a, 14a formed in the frame members and inner surfaces of the mounting brackets 15, 16 when the electric motor 11 is fixed to the mounting brackets 15, 16 by the screws 17. The presence of such gaps produces vibration or unusual sounds upon driving of the electric motor 11. Moreover, if the frame members 13, 14 are fixed to the mounting brackets 15, 16 in a condition accompanying a dimensional error, there is a risk that the fixed portions are subjected to stresses (tensile forces) and durability of the fixed portions is deteriorated. In addition, when the frame members 13, 14 are fixed to the electric motor 11 by caulking, stresses are caused so as to act on not only the fixed portions but also the caulked portions, thus giving rise to a risk that the caulked portions may be broken. Those problems have been experienced in the technical field regarding the invention.